security/py-acme: Update to 0.0.0.dev20151104

• Update version and distinfo checksum (0.0.0.dev20151104)
• Switch to DISTVERSION (illegal PORTVERSION) and DISTVERSIONPREFIX
• Use github version tags rather than a direct commit

PR: 204303
Approved by: Carlos J Puga Medina <cpm fbsd es> (maintainer)